Arvind Kannan

Human Colon and Liver Cancer Cell Proliferation Inhibition by Peptide Hydrolysates Derived from Heat-Stabilized Defatted Rice Bran

Rice bran, an economical, underutilized coproduct of rough rice milling, was used to produce peptide hydrolysates, which were investigated for anticancer activity. Protein hydrolysates prepared by Alcalase hydrolysis under optimized conditions were treated further to obtain gastrointestinal (GI)-resistant peptide hydrolysates. They were fractionated into >50, 10-50, 5-10, and <5 kDa sizes and evaluated for inhibitory activity on proliferation of human colon (Caco-2) and liver (HepG2) cancer cell lines by Trypan blue dye exclusion assay. GI-resistant <5 and 5-10 kDa sized peptide fractions inhibited growth of Caco-2 cells by 80%, and the <5 kDa fraction inhibited growth of HepG2 cells by approximately 50% compared to controls and nonresistant fractions. An MTS cell titer assay confirmed antiproliferative effects of the peptide fractions. The results demonstrated that 5-10 and <5 kDa sized GI-resistant fractions promoted significant (p < 0.05) inhibitory activities on both cancer cell lines compared to controls. More investigations are needed to show such value-added effects on the technofunctional and sensorial properties of the food protein and peptide matrices.

Human cancer cell proliferation inhibition by a pentapeptide isolated and characterized from rice bran

Food-derived bioactive peptides promote functional activity against diseases and present as nutraceutical agents. The purpose of our research was to isolate and fully characterize peptide(s) derived from rice bran having anti-cancer properties. Gastrointestinal juices resistant peptide fractions were initially generated from heat stabilized de-fatted rice bran from which <5 kDa fraction was shown to inhibit proliferation of cancer cells. Based on these published findings the <5 kDa peptide fraction was selected for further characterization to obtain single pure peptide(s) with enhanced anti-cancer properties. Purification and characterization from the fraction was done employing chromatography and mass spectrometric techniques. Cancer cell viability was measured using a cell titer assay that uses a tetrazolium dye [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt; (MTS)] and the electron coupling reagent, phenazine methosulfate. Ion-exchange chromatography elutes that showed anti-cancer properties were further purified to liberate pure peptide. The pure peptide at 600-700 microg/mL dose caused 84% inhibition to colon cancer cells (Caco-2, HCT-116) growth, 80% to breast cancer cells (MCF-7, MDA-MB-231) growth and 84% to liver cancer cells (HepG-2) growth. Mass spectrometry analysis and de novo sequencing revealed the sequence of Glu-Gln-Arg-Pro-Arg for the peptide with a molecular mass of 685.378 Da. A novel pentapeptide was isolated from rice bran to possess cancer growth inhibitory properties on colon, breast, lung and liver cancer cells. This peptide could serve as a nutraceutical agent against cancer.

Shrimp shell peptide hydrolysates inhibit human cancer cell proliferation.

BACKGROUND Shrimp wastes contain high-quality protein that is underutilized, and particularly peptides derived from shrimp wastes (normally used as animal feed) have not been utilized for bioactive properties. Hence the objective was to utilize shrimp waste proteins in generating peptides and to investigate these for cancer antiproliferative activities. The objectives involved hydrolyzing shrimp proteins (intact in shell) using a food-grade Cryotin enzyme, obtaining gastrointestinal resistant peptides, fractionation to generate < 10, 10-30 and > 30 kDa fractions, and evaluating for colon and liver cancer cell growth inhibitory effects. Three shrimp shells--whole langostino lobster shells from El Salvador (South America), shrimp shells from St Petersburg, FL (USA), and shrimp shell whites from the Gulf of Mexico, LA (USA)--were evaluated for the study. RESULTS Peptide fractions (<10 and 10-30 kDa) obtained from shrimp shell whites (Gulf of Mexico) as well as from langostino shells (El Salvador) significantly inhibited the growth of both colon and liver cancer cells by 60%, while < 10 kDa fraction from shrimp shells (FL) inhibited growth of liver cancer cells alone by 55%, compared to controls. CONCLUSION The promising anticancer peptide fractions from shrimp waste proteins has the potential for novel nutraceutical ingredient applications.

Colon and Breast Anti-cancer Effects of Peptide Hydrolysates Derived from Rice Bran

Rice bran is an economical, under-utilized co-product of rough rice milling. The objective of this study was to produce rice-bran peptides and investigate for anti-cancer activity. Protein hydrolysates were prepared by treating heat stabilized defatted rice-bran with food grade Alcalase enzyme, followed by treatment with simulated gastric and intestinal juices to obtain resistant peptides. Resistant peptides were fractionated into >50, 10-50, 5-10, and <5 kDa sizes, freeze dried, and evaluated for inhibitory and cytotoxicity activities on human colon (HCT-116) and breast (HTB-26) cancer cell lines. The results showed that <5 kDa fraction of rice-bran is a potent anti-cancer agent. The cytotoxicity of the fraction to both cancer cell types was more pronounced after the treatment with 500 � g/mL. The IC50 of the peptide fraction was ap- proximately 750 � g/mL. These results indicate that the <5 kDa peptide fraction separated from rice bran protein hydro- lysate has a potent anti-tumor activity for colon cancer cells. The peptide fractions that demonstrate anti-cancer activities have the potential for use as functional food ingredients for health benefits.

Functional properties and Angiotensin-I converting enzyme inhibitory activity of soy–whey proteins and fractions

Soy proteins when prepared to high purity can confer good functional properties and the whey by-product is a potential source for bioactivity. In this study, we determined the protein, moisture, fiber, solubility, foaming, emulsion properties, as well as Angiotensin-I converting enzyme (ACE-I) inhibitory activity of prepared soy-whey proteins and its fractions. The soy-whey proteins were fractionated into <5, >5, >10, and >50kDa using ultrafiltration. The expanded AACC methods were used to determine protein, moisture, and fiber analyses of the whey and its fractions. Solubility method was conducted to determine the protein solubility profile of the soy-whey and its fractions at varying pHs. Turbidimetric method was used to evaluate emulsifying activity (EA) and emulsion stability (ES). There were significant differences observed in moisture, protein and salt contents between unfractionated, >50kDa and smaller sized fractions. No significant differences were observed with phytic acid and total dietary fiber contents among all samples. The unfractionated whey protein and >50kDa fraction showed better solubility than other fractions. Unfractionated whey protein had the highest foam capacity (42.7mL) while the fraction >5kDa showed the greatest foaming stability (46min). The highest emulsion activity (0.33±0.1) and stability (825.1±45.1) was obtained with the >50kDa fraction while the unfractionated whey protein had the highest ACE-I inhibition activity. The findings indicate that soy-whey protein fraction (>50kDa) had good solubility, emulsion activity and stability, while the unfractionated whey protein exhibited the strongest ACE-I inhibition percentage (19%).